Questions about relays and power supplies

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fallingsky
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Questions about relays and power supplies

Post by fallingsky »

So despite my best efforts to search and read any and all related posts so as to sound less like an idiot, I still have some very rudimentary questions about how different parts of the BCS controlled system are powered. I am about to order the last bits of equipment and I need to get this thing up and running soon. So here is my basic understanding of the power and wiring setup. I am going to have 3 BCS units. I will be using all 8 temp sensor inputs for each board, and almost all of those inputs will be linked to an output controlling 12 VDC motorized ball valves. I had made an earlier post about UL listing and needing to do 24 VAC, but I think I can be fall under the low voltage, power-limited exemption. We are a pre-existing brewery and are only using these for fermentation temp control with glycol, nothing dangerous like steam. Anyway. Here is my current plan, along with some questions. Sorry if some are obvious, as I don't even have my BCS units yet, anxiously waiting for them to arrive.

5V wall wart to power the BCS
Q : If I am using 3 BCS units and putting them in the same DIN rail box, is there a power supply I can use that could power all three? Or could I just split the wires on a power supply with a higher mA rating with the same voltage? How many mA does each BCS draw at max? Or is it dangerous to use a PS with a higher amperage rating than the one that comes with my BCS?

BCS inputs will be wired to 10K thermistors via 22/2 AWG twisted pair shielded cable. Considering running some of the common length of the sensor runs along Cat5e cable and then splicing to the individual tanks with the 22/2. Is there any problem with transitioning from 24 to 22 AWG? Any recommendations on the type of terminals that they have used for success with this type of transition would be appreciated as well. I don't want to use M12 connectors. I may just run individual lines for each temperature sensor to be safe. Would rather only lose one tank if a wire gets damaged instead of 4-7.

BCS outputs will be wired to the inputs of these relay boards, and between here and the motorized ball valves is where the bulk of my questions lie.

These are the relay boards I am planning on getting, one of each:
http://www.amazon.com/gp/product/B00M1I ... MUS055KMW5
http://www.amazon.com/gp/product/B00M1M ... MUS055KMW5

And these are the motorized ball valves. The wiring type is CR04, so it is a 2 wire system with automatic spring return to the off position when power is cut:
10 of these
http://www.amazon.com/gp/product/B00Y42 ... ge_o00_s00
6 of these
http://www.amazon.com/gp/product/B00D6F ... ge_o01_s00
10 of these
http://www.amazon.com/gp/product/B00D6F ... ge_o01_s00

So do I just need a 12V power supply to power the relay boards at the VCC/Ground input, and the relay board distributes the power to run the actual ball valves, or am I missing piece of hardware and I need to provide power from the power supply to each ball valve and the relay just does the switching? How much amperage should I be supplying to the relay boards? Basically I'm just wondering what kind of powersupply I should be buying to operate the system I have outlined. Here are some that I have looked at.

Could this be used for both BCS and relays?
http://www.digikey.com/product-detail/e ... ND/4833507

Or if I needed to supply individual power to each of the ball valves would I need to use something like this:
http://www.amazon.com/dp/B00NBDEN9M?psc=1


This one looks like it would be the best best to pass the eye test that our systems was a legit "power limited" system underneath the 100VA and 30V requirements. Do you think it would be enough power for all those ball valves? Or I could use 2 and would 1 at least be able to power everything on the 16 relay?
http://www.amazon.com/SANPU-Constant-Vo ... pply+8+amp

Okay. I know I'm missing something else but my head is swimming now and I need a break while I await y'alls insight and wisdom. Thanks for all you do!
fallingsky
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Re: Questions about relays and power supplies

Post by fallingsky »

Or this one, which also stays under 100 W and would actually get to me on time!
http://www.amazon.com/SANPU-Constant-Vo ... pply+8+amp
JonW
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Re: Questions about relays and power supplies

Post by JonW »

fallingsky wrote:5V wall wart to power the BCS
Q : If I am using 3 BCS units and putting them in the same DIN rail box, is there a power supply I can use that could power all three? Or could I just split the wires on a power supply with a higher mA rating with the same voltage? How many mA does each BCS draw at max? Or is it dangerous to use a PS with a higher amperage rating than the one that comes with my BCS?
I would suggest you stay with the BCS provided power supplies. The BCS can be a little finicky with it's power requirements so by using the provided ones, you eliminate an area of potential issues. I would suggest just using some DIN mounted outlets inside your enclosure like this: http://www.amazon.com/IMACP01-Grounded- ... ref=sr_1_1
fallingsky wrote: BCS inputs will be wired to 10K thermistors via 22/2 AWG twisted pair shielded cable. Considering running some of the common length of the sensor runs along Cat5e cable and then splicing to the individual tanks with the 22/2. Is there any problem with transitioning from 24 to 22 AWG? Any recommendations on the type of terminals that they have used for success with this type of transition would be appreciated as well. I don't want to use M12 connectors. I may just run individual lines for each temperature sensor to be safe. Would rather only lose one tank if a wire gets damaged instead of 4-7.
I would suggest using individual runs if possible.

fallingsky wrote: BCS outputs will be wired to the inputs of these relay boards, and between here and the motorized ball valves is where the bulk of my questions lie.
The relay boards and valves spec'd look good. I really like those relay boards from Electronics Salon. My new rig has their DIN ones like those.

Any of the power supplies you listed would work fine. Each one of those valves uses about 100ma of current and you'd never be running them all at the same time. Anything in the 3-4 amp range will work.

Your wiring from the power supply should go to a wiring terminal strip. From there you can individual jumpers feed the center common connector of each relay. The switched output (N/O) connector on the relay would then go to the valve. To make running the grounds easier, you might want to use a terminal strip for that as well. If you were to just bunch up all the ground leads and tie them together with a wire nut, it would work, but you'd have to undo it if you ever wanted to service one valve. It would be best to use the terminal strip for the grounds so you only disconnect the valve needed.
BrunDog
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Re: Questions about relays and power supplies

Post by BrunDog »

Just sharing... I used two power supplies: one 5 V and one 24V. I turned the output on the 5V up all the way and it supplies about 5.8V to the BCS, an Arduino, and two four-pack relay boards. The 24V supply powers a capacitive sight glass sensor, 5 motorized ball valves, and 1 proportional valve. I went with 24V because the valves and sensor were 24V, and I find this to be a more universal power. Used these supplies: https://www.digikey.com/product-detail/ ... ND/1631413

Make sure you tie the power supply grounds together at a common ground point.

The Electronics Salon boards are "high-trigger", aka PNP or sourced. This is important as the BCS has high-on outputs, so do not switch brands without researching. I used these with success (5V) as I had a space constraint and could not fit the ES boards: http://www.amazon.com/gp/product/B00QC6C3UQ. The ES boards will trigger above 2.5V, so these will work well whether you use 5V, 12V, or 24V boards. Of course, the board voltage is just the requirement for the relay. The relay poles can switch any power inside the relay specification - even 240V AC.

Caveat as noted on those valves... they use capacitors to store a charge to have the valves return on switch off... these cost more and will always return on power loss. They also take a bit more current on power-up, and if they do not get a chance to charge, may not return. You might consider a different configuration (positive powered, like CR03 or CR02), since you have double throw relays. They may use less power and are positive acting. On a power drop, they will not switch, which may be important in the middle of a brew.

Anyway, just throwing ideas/considerations out there.

-BD
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